A comparative study of a combination of zidovudine, didanosine and double blinded nevirapine versus a combination of zidovudine and didanosine.This study has closed. Analysis from the data of 398 enrolled patients showed that the addition of nevirapine (NVP) to ZDV + DDI gave moderate benefits on both CD4 count and virala infectivity in peripheral blood mononuclear cells (pbmc) which were sustained over 48 weeks. Benefit was also seen in plasma HIV-1 RNA levels.